1. Field of the Invention
The present invention relates generally to an image forming apparatus utilizing electro-photographic technology such as a copier, printer, and facsimile, and, more particularly, to technology for removing adhering substances in the image forming apparatus.
2. Description of the Related Art
Intermediate transfer is widely employed in image forming apparatuses. This technique includes a primary transfer that includes transferring a toner image formed on an image carrier to an intermediate transfer body, and a secondary transfer that includes transferring the toner image on the intermediate transfer body to a transfer material. To allow the primary transfer, the image carrier and the intermediate transfer body are in physical contact with each other. Moreover, generally, the image carrier and the intermediate transfer body can also directly or indirectly contact with other members. These members can be a transfer material, e.g., paper, and a rubber member, e.g., rollers and the like.
Various types of paper and various types of fiber portion of an ingredient and wide variety of additives to be added are used in image forming apparatuses. In image forming apparatuses, paper powders are produced due to friction of the paper with rubber rollers and the like when the paper is carried inside the apparatus. The paper powder is a common cause of failure of the image forming apparatuses. Especially, it is known that talc contained in the paper adheres to surfaces of the image carrier and the intermediate transfer body and cause a change in surface nature and surface resistance conditions of these members. This results in a distorted image. Moreover, an ingredient of the rubber of the rubber rollers may exude and contaminate the surfaces of the image carrier and the intermediate transfer body, resulting in distortion of images or deterioration of the surface natures.
Japanese Patent Application Laid-Open Publication No. 1998-312143 discloses an image forming apparatus that sequentially transfers images formed on an image carrier, such as a photoreceptor, onto a paper. This image forming apparatus includes a surface-stain detection unit that detectes, after development but before cleaning, surface stains on the image carrier, and a control unit that periodically operates the surface-stain detection unit, and, when an output value of the surface-stain detection unit falls below a predetermined value, that provides a control to form a toner image on an entire width of an image forming portion of an image carrier. Therefore, the surface stains are periodically detected by the surface stain detection unit, and when the output value becomes a predetermined value or less, a toner image is formed on the image carrier and fine powders aggregated on the image carrier can be removed along with toner of the toner image at the time of cleaning.
Various techniques have been used to solve the above problems. In a first technique, a rubber blade is used to clean the surfaces of the image carrier and the intermediate transfer body. When a rubber blade used, adhering substances can be cleaned more effectively by increasing an abutting pressure of the rubber blade to the image carrier and the intermediate transfer body. However, the rubber blade can chip-off, or scratch, the surfaces of the image carrier and the intermediate transfer body, which can result into streaky abnormal images. Moreover, the rubber blade itself is eaten-up is when the abutting pressure is increased.
In a second technique, a brush member and the like is used to clean the surfaces of the image carrier and the intermediate transfer body. However, the space and cost for additionally providing the brush member is problematic. Moreover, a means to collect adhering substances from the brush member itself becomes necessary. This leads to increase in size, complicatedness, and cost of the image forming apparatus.